Revolving center for lathes and the like



Jan. 3, 1939. F|$H REVOLVING CENTER roa Lmms m mm LIKE Filed Jan. 25, 1938 I mwmww w m sq 1 I W R M m? I M 1 II mm I I H M I I I. m Rx. I I d L I m Q\ R NJ R 7| U m MEWELH I w Y &\ E w H Q m ATTORNEYS Eatented Jan. 3',- 1 939- UNITED STATES PATENT OFFICE Thomas Fish, Bridgepcrt; 001m. Applieaticn January 25, 1938, Serial No. 186,761

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- My invention relates to a new and improved revolving center for lathes, grinders, and other machine tools.

One of the objects of the invention is to pr 5 vide' a center having a double-row angularcontact preloaded bearing adjacent the frontend of the center. and having a single-row bearing or double-row bearing at the rear end of the center. The anti-friction bearing at the rear end of the center may be preloaded or not preloaded.

The combination of the aforesaid bearings stabilizes the center and gives the center greater is resistance to lateral pressure or radial pressure, namely, pressure which is perpendicular to or inclined to the longitudinal axis of the center. Another objectis to provide a center with a bearing of the preloaded type at its front end, so and with a self-aligning bearing at the rear end of the center, said self-aligning bearing being a double-row ball-bearing or roller-bearing, or a single-row ball-bearing or roller-bearing. As stated previously, the hearing at the rear end of the center may or may not be preloaded. Another object is to provide a center which is self-aligning, so that if excessive load is imposed upon the center the deflection o! the shank of the center from its true position is prevented .or lessened."

The improved device is also useful in preventing excessive wear on the anti-friction bearin or bearings, ii the shank of the center bends or is deflected from its true podtion by reason of excessive 1.

Other ohjectsoimy invention will he set forth in the description and drawing which illustrate a preierred' in went thereof, it being unders that the ahcvestatement of the objects 01 my invention is intended generally to I explain the same without limiting it in any- .manner.

Fig. l is a perspective view of the improved device. v

Fig. 2 is a section, 7 in elevation, 65 through the longitudinal axis of said device.

Fig. 3 is a sectional viewof the rear end of the the ti. .t. oi thespindle of the device can automatically adjust itseli in use to deflection. The device has a casing l which is provided with an enlarged head l6. Bald casing i is mounted in the tall atock oi a lathe or the like.

saidcasing l isclosedbymeansotacaplwhich isconnectedtotherearendoithecasingiby means oi suitable cooperating threading. The

device, showi in greatly exaggerated form how casing i has its inner wall provided with a shoulder against which the end wall of a retainer i8 is clamped, by means of the cap 2 and an int mediate member I. The member is may be an ordinary split metal washer made of resilient 5 metal. The retainer it may fit tightly against the corresponding part of the inner wall of the housing or casing I. Said retainer i6 may have a drive lit in the casing I, so as to prevent it from turning in the casing i. m

The inner wall of the retainer-i6 has longitudinal surface elements which may be either straight or of concave shape. That is, the line of intersection between the surface of said inner w wall, and every plane which passes through the central longitudinal axis of spindle ii, may be either straight or concave. Said surface elements, either straight or concave, are identical. The outer wall of the outer race Ila is corre-- 2o spondingly shaped, so thatmembers Fla. and i6 interflt. The innerrace i1 is suitably connected to the reduced shank portion la, by a drive fit, or the like. Anti-friction bearings iii are located between the races 11 and "a in the usual man- 25 ner. I have shown one row of roller-bearings, but I can use one row or more than one row of ball-bearings, of roller-bearings, etc.

Therefore, it said surface elements are rounded, the outer race I la can turn relative to the re-'- 30 tainer I, in unison with inner race I'l, about a point which is indicated by the inner end of the lead-line oi the reference numeral 30 in Fig. 3, from the position shown in Fig. 2 to the position shown in Fig. 3. This lateral turning is greatly exaggeratedin Fig. 3. It the longitudinal surface elements of the inner wall of member is are concave, the longitudinal surface elements of the outer wall of member "a are convex. I

The head la is provided with an outer race i which may have a tight flt therein, so that the outer race will not turn in said head. The inner face la is connected in the usual manner-to the head 3b of the spindle 3. Anti-friction bearings it are located between the races I and la. These gs are t: but any other type may be As shown in Fig. 2, the balls l0 have portions at their surfaces abutting the wall of an ex tension of the inner wall of member 1. m Preloaded s-per as are well-mown. In making a preloaded bearing of the double-row type, one row 01' the ballsis assembled with its retainer and with theraces under no pressure. so that there is a slight play. until the second row of balls has been inserted. together with its retainers. The bearing is designed so that it has a minus tolerance for both rows of balls, so that it requires pressure to insert the last two or three .balls of the second row, This is done by means of a press. The second row of balls has the usual inner and outer retainers which are connected to each other after all the balls of the second row have been inserted. A preloaded bearing of this type has considerable binding effect until the effect of the preloading has been relieved by means of a thrust which is parallel to the axis of revolution. This is the type of bearing which I use at the front end of the center.

The head Id of the casing is provided with the usual cap 5, which is connected by means of screws 6 to the end wall of said head la. The

metal cap 5 clamps a metal washer 9 in position. Said washer 8 is provided with packing discs II which abut the annular enlargement ii of the spindle 3. A sealing washer l2, made of metal, is located between the annular enlargements I4 and I5 of the spindle I. The spindle 3 is provided' with a head 4 of any suitable shape. a

The interior of the casing I maybe filled with any suitable lubricant which is prevented from leaking out of said casing by means of the packing washers II, the cap 2, and the members 5 and 9. When cap 5 is clamped in position, its tapered wall-portion thrust the edges-of discs ll against members 9 and I5.

when the device is used, the load is usually inclined to the axis of revolution of spindle I,

' so that said load has a component which is parallel to the axis, and a component which is perpendicular to the axis. The parallel component relieves the binding effect of the preloading of the hearing at the front end 'of the spindle. The other component tends to deflect the spindle from its true position, which is shown in Fig. 2.

This deflection is resisted by the preloaded double-row hearing at the front end of the spindle, and also by the bearing at the rear end of this spindle. This radial load will cause the spindle to deflect slightly between the bearing at the front end and the bearing at the rear end,

so that the spindle is no longer truly straight. This deflection is accommodated by the design of the bearing which is shown in Fig. 3, thus preventing said bearing from binding and becoming excessively heated. The design of the bear: ing at the rear end may be varied from the specific example given, in order to make the center self-aligning.

However, I do not wish'to be limited to a rear bearing of the preferred type, because the combination of a preloaded double-row angular-contact hearing at the front end, with a single row or double row anti-friction bearing of any type at.

the rear end, is included in the invention.

I do not wish to be limited to the specific shape of the retainer l8 specified herein, although this is preferable. The invention generally covers every type of bearing in which the spindle is self-aligning.

I have shown a preferred embodiment of my invention, but it is clear that numerous changes and omissions can be made without departing from its spirit.

While the invention is particularly useful in connection with a revolving center, it is also applicable to other uses so that the invention is not to be restricted to the specific 911 11 or in the specific device which is stated in the description or in the claims.

The common center point of the concave longitudinal surface elements of the inner wall of the retainer l6 may be defined as the intersection between the axis of revolution of the member 3, and a plane which .is perpendicular to said axis and which passes through the median line of the retainer 18. Said median line is a circle which is equally spaced from the front end and from the rear end of said retainer it.

While I have referred to the member l6 as a retainer, said member IS in effect serves as a bearing for the outer wall of the outer race Ha, so as to permit relative movement between said members Ila and I8 when the spindle is deflected from its true position.

When the spindle is deflected from its true position, the bearing for saldspindle moves relative to the casing in what may be designated as a lateral direction, since said direction is lateral to a plane which is perpendicular to the axis of revolution of the spindle.

I claim:

1. A revolving center comprising a casing, a turnable spindle located in said casing and having its front end portion projecting from said casing, a-double-row angular-contact preloaded anti-friction bearing located in the front of the casing and between said casing and the adjacent front portion of the spindle, and an additional anti-friction bearing located in the casing and between the casing and the spindle, said additional bearing being spaced rearwardly from said double-row bearing.

2. A revolving center comprising a casing; a turnable spindle located in said casing and having its front end-portion projecting from said casing, a double-row angular-contact preloaded antifriction be'aring located in the front of the casing and between said casing and the adjacent front portion of the spindle, and an additional anti-friction bearing located in the casing and between the casing and the spindle, said-additional bearing being spaced rearwardly from said double-row bearing, the additional bearing being shaped to move laterally relative to the casing when the spindle is deflected from its true position. 1

3. A revolving centercomprising a casing, a turnable spindle located in said casing and hav ing its front end-portion projecting from said casing, bearing means located in the front-portion of the casing between the inner wall of the casing and the adjacent front-portion of the spindie, and an additional anti-friction bearing located in the casing between the inner wall of the casing and the spindle, said anti-friction bearing being spaced rearwardly from said bearing means, said anti-friction bearing being shaped to move laterally relative to the casing when the spindle is deflected from its true position.

4. A revolving centercomprislng a casing, a turnable spindle located in said casing and having its front end-portion projecting from said casing. bearing means located in the front-portion of the casing between the inner wall of the casing and the adjacent front-portion of the spindle, .and an additional anti-friction bearing located in the casing between the inner wall of the casing and the spindle, said anti-friction bearing being spaced rearwardly from said bearing means, said anti-friction bearing l'eing shaped to turn relative to the casing about a point which is located substantially on the axis of revolution of the spindle. f

- HI'HOMAS FISH.- 

